A difficult problem faced by board designers is their need to make test-related design decisions before their board design is complete. This decision process is known as Design for Testability (DFT). The problem is difficult in that board designers are often not test experts and therefore have little or no understanding of how their boards are actually tested. Even for test experts, the large size and complexity of some boards make it difficult to see the effects of design tradeoffs with respect to testing. Unfortunately, once a design is complete, DFT changes may be difficult to justify in terms of re-design expense and/or the impact of any changes on a board's design schedule.